
/* mixin */
@mixin bg($w:100%,$h:100%,$po:center center){
  width: $w;
  height: $h;
  background-position: $po;
  background-repeat: no-repeat;
}
@mixin pos($t,$l,$pos:absolute){
  position: $pos;
  top: $t;
  left: $l;
}
@mixin pach($c){
  &:-moz-placeholder, textarea:-moz-placeholder { color: $c; }
  &::-moz-placeholder, textarea::-moz-placeholder { color: $c; }
  &:-ms-input-placeholder, textarea:-ms-input-placeholder { color: $c; }
  &::-webkit-input-placeholder, textarea::-webkit-input-placeholder { color: $c; }
}